Wireless power delivery has been an active field of research. NASA has been working on systems to use high intensity lasers to power small UAVs or Vehicles. Due to laser safety regulations, however, such systems have a limited power delivery capability. While high intensity laser are used in the industry, their use is restricted in closed environments where people are not present. Laser radiation injury is mainly caused by thermal damage to the living tissue.
While laser skin burns only happen under extremely powerful laser beams, human retina is quite sensitive and can damage under much lower intensities. The IEC60825 is an international standard that specifies the limits and classes of lasers. Based on the IEC60825 standard, the maximum permissible exposure (MPE) at the human cornea depends on both the laser energy and duration of exposure. FIG. 1 shows a plot of MPE for different wavelengths at different exposure times, and assuming that the power is concentrated directly at the cornea.